SYSTEMS AND METHODS FOR MONITORING NEUROSTIMULATION DOSING

• US 20130245718A1
• Filed: 02/28/2013
• Published: 09/19/2013
• Est. Priority Date: 03/19/2012
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Birkholz, Doug M., Brandner, Douglas J., Gifford, Douglas J., Ternes, David J., Linder, William J.
• Granted Patent: US 8,965,521 B2
• Time in Patent Office: Days
• US Class Current: 607/59
• CPC Class Codes: A61N 1/3605 Implantable neurostimulators for stimulating central or peripheral nerve system
• CPC Class Codes: A61N 1/36082 Cognitive or psychiatric applications, e.g. dementia or Alzheimer's disease
• CPC Class Codes: A61N 1/36125 Details of circuitry or electric components
• CPC Class Codes: A61N 1/36142 for improving safety
• CPC Class Codes: A61N 1/36178 Burst or pulse train parameters
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: A61N 1/378 Electrical supply

Abstract

Various implantable device embodiments may comprise a neural stimulator configured to deliver a neurostimulation therapy with stimulation ON times and stimulation OFF times where a dose of the neurostimulation therapy is provided by a number of neurostimulation pulses over a period of time. The neural stimulator may be configured to monitor the dose of the delivered neurostimulation therapy against dosing parameters. The neural stimulator may be configured to declare a fault if the monitored dose does not favorably compare to a desired dose for the neurostimulation therapy, or may be configured to record data for the monitored dose of the delivered neurostimulation therapy, or may be configured to both record data for the monitored dose of the delivered neurostimulation therapy and declare a fault if the monitored dose does not favorably compare to a desired dose for the neurostimulation therapy.

Claims

1. A method, comprising:

delivering a neurostimulation therapy, wherein a dose of the neurostimulation therapy is provided by a number of neurostimulation pulses over a period of time;

monitoring the dose of the delivered neurostimulation therapy; and

declaring a fault if the monitored dose does not favorably compare to a desired dose or recording data for the monitored dose of the delivered neurostimulation therapy.

2. The method of claim 1, wherein:

delivering the neurostimulation therapy includes using a hardware state machine with hardware registers to deliver a train of neurostimulation pulses for each of a plurality of neurostimulation bursts; and

monitoring the dose of the delivered neurostimulation therapy includes providing a Burst Start Interrupt from the state machine at a beginning of the neurostimulation bursts and a Burst Stop Interrupt from the state machine at an end of the neurostimulation burst, starting a stimulation ON timer in response to the Burst Stop Interrupt; and

declaring the fault if, after a defined number of times, the stimulation ON timer expires before the Burst Stop Interrupt occurs.

3. The method of claim 1, wherein:

delivering the neurostimulation therapy includes using a hardware state machine with hardware registers to deliver the train of neurostimulation pulses; and

monitoring the dose of the delivered neurostimulation therapy includes providing a Burst Start Interrupt at a beginning of the neurostimulation burst and a Burst Stop Interrupt at an end of the neurostimulation burst, and starting a stimulation OFF timer in response to the Burst Stop Interrupt; and

declaring the fault includes declaring the fault if, after a defined number of times, the Burst Start Interrupt occurs before the stimulation OFF timer expires.

4. The method of claim 1, wherein:

delivering the neurostimulation therapy includes using a hardware state machine with hardware registers to deliver the train of neurostimulation pulses; and

monitoring the dose of the delivered neurostimulation therapy includes using firmware to count delivered pulses; and

declaring the fault includes declaring the fault if the count of the delivered pulses is not within a defined count threshold.

5. The method of claim 1, wherein monitoring the dose of the delivered neurostimulation therapy includes:

setting a stimulation status bit based on whether a burst of neurostimulation pulses is being delivered; and

declaring the fault if a status of the status bit does not match an expected status for the burst of neurostimulation pulses.

6. The method of claim 1, wherein monitoring the dose of the delivered neurostimulation therapy includes sampling the delivered neurostimulation therapy at a sampling frequency, and monitoring the samples against expected values for the neurostimulation therapy and the sampling frequency.

7. The method of claim 1, wherein delivering the neurostimulation therapy includes blocking, after a given pulse in the train of neurostimulation pulses, subsequent pulses for a programmable period, and declaring the fault includes declaring the fault after blocking a pulse or a defined number of pulses in a defined period of time.

8. The method of claim 1, wherein:

delivering the neurostimulation therapy includes using a stimulation configuration to deliver the neurostimulation therapy, wherein the stimulation configuration includes two or more parameters;

monitoring the dose of the delivered neurostimulation therapy including using the two or more parameters to characterize safe and potentially unsafe stimulation; and

declaring the fault includes declaring the fault for potentially unsafe stimulation.

9. The method of claim 1, wherein monitoring the dose of the delivered neurostimulation therapy includes:

monitoring charge depletion for a time period and comparing the monitored charge depletion against a limit;

or

monitoring charge depletion for time periods, wherein for each time period monitoring includes determining a rolling average of charge depletion, and comparing the rolling average of charge depletion against a limit.

10. A method, comprising:

delivering a neurostimulation therapy with stimulation ON times and stimulation OFF times, wherein;

delivering the neurostimulation therapy includes delivering a neurostimulation burst during the stimulation ON time and withholding neurostimulation during the stimulation OFF times;

the neurostimulation burst includes a train of neurostimulation pulses with a pulse frequency;

a dose of the neurostimulation therapy is provided by a number of neurostimulation pulses over a period of time, and

delivering the neurostimulation therapy includes delivering a train neurostimulation pulses using a hardware state machine with hardware registers and at least one oscillator;

monitoring the dose of the delivered neurostimulation therapy,

wherein monitoring includes;

providing a burst-start hardware interrupt at a beginning of the neurostimulation burst and a burst-stop hardware interrupt at an end of the neurostimulation burst, and timing time between interrupt;

performing a deviation check for the at least one oscillator;

using firmware to count delivered pulses;

using stimulation status bits and comparing the stimulation status bits against the stimulation ON times or stimulation OFF times.

11. An implantable medical device, comprising:

a neural stimulator configured to deliver a neurostimulation therapy with stimulation ON times and stimulation OFF times, wherein a dose of the neurostimulation therapy is provided by a number of neurostimulation pulses over a period of time;

wherein the neural stimulator is configured to monitor the dose of the delivered neurostimulation therapy against dosing parameters, and declare a fault if the monitored dose does not favorably compare to a desired dose for the neurostimulation therapy or record data for the monitored dose of the delivered neurostimulation therapy.

12. The device of claim 11, wherein the neural stimulator includes:

a clock with an oscillator;

a hardware state machine operationally connected to the clock to provide pulse timing control signals, wherein the state machine includes hardware registers;

pulse circuitry configured to receive the timing control signals and deliver neurostimulation pulses with a pulse frequency;

a programmable processor programmed with code to control a neurostimulation therapy with stimulation ON times and stimulation OFF times, wherein the programmable processor writes the hardware registers in the state machine, and the state machine uses the hardware registers to provide the pulse timing control signals; and

a power supply configured to provide electrical power to operate the device.

13. The device of claim 12, wherein:

the state machine is configured to provide a Burst Start Interrupt at a beginning of stimulation ON times and a Burst Stop Interrupt at an end of stimulation ON times;

the processor includes a stimulation ON timer; and

the processor is configured to declare a fault if, after a known number of times, the stimulation ON timer expires before the Burst Stop Interrupt occurs.

14. The device of claim 12, wherein:

the state machine is configured to provide a Burst Start Interrupt at a beginning of stimulation ON times and a Burst Stop Interrupt at an end of stimulation ON times;

the processor includes a stimulation OFF timer; and

the processor is configured to declare a fault if, after a known number of times, the Burst Start Interrupt occurs before the stimulation OFF timer expires.

15. The device of claim 12, wherein:

the state machine is configured to provide a burst-start interrupt at a beginning of the neurostimulation burst and a burst-stop at an end of the neurostimulation burst;

the device includes a pulse counter configured to count pulses from the burst-start interrupt and the burst-stop interrupt; and

the processor is configured to declare a fault if the count is not within the dosing parameters.

16. The device of claim 12, wherein the pulse circuitry includes an output limiter.

17. The device of claim 12, wherein the device is configured to:

monitor charge consumption, and declare a fault if the charge consumption is not within the dosing parameters;

or

perform an oscillator deviation check and declare a fault if the oscillator does not pass the deviation check.

18. The device of claim 12, wherein:

the device is configured to perform an oscillator deviation check and declare an oscillator deviation fault if the oscillator does not pass the deviation check;

the state machine is configured to provide interrupts, including a Burst Start Interrupt at a beginning of stimulation ON times and a Burst Stop Interrupt at an end of stimulation ON times;

the device includes at least one stimulation timer configured to time a period between interrupts, and the device is configured to declare a fault if the time does not favorably compare to a defined time;

the device includes a pulse counter, and the device is configured to declare a fault if the count does not favorably compare to a defined count;

the device is configured to monitor charge consumption, and declare a fault if the charge consumption does not favorably compare to a defined charged consumption; and

the pulse circuitry includes an output limiter configured to limit a pulse frequency for the neurostimulation pulses.

19. The device of claim 12, wherein the device is configured to perform a device action in response to the fault, wherein the device action includes stopping or altering the neurostimulation therapy in response to the fault.

20. A system, comprising:

an implantable medical device, wherein the implantable medical device includes;

a neural stimulator configured to deliver a neurostimulation therapy with stimulation ON times and stimulation OFF times, wherein the neurostimulation therapy includes a neurostimulation burst during the stimulation ON time and no neurostimulation during the stimulation OFF times, and the neurostimulation burst includes a train of neurostimulation pulses with a pulse frequency, and a dose of the neurostimulation therapy is provided by a number of neurostimulation pulses over a period of time;

wherein the neural stimulator is configured to monitor the dose of the delivered neurostimulation therapy against dosing parameters; and

a programmer, wherein the programmer and the implantable medical device are configured to communicate with each other, and the programmer is configured to program parameters for the neurostimulation therapy into the implantable medical device, wherein the programmer is programmed with interactive limits configured to limit programming of the parameters for the neurostimulation therapy.